Compressor governor



Patented Jan. 18, 1944 UNITED STATES COMPRESSOR GOVERNOR William Duckworth, Hamilton, Ontario, Canada,

assignor to The Westinghouse Air Brake Company, Wilmerding, Pa., a corporation of Pennsylvania Application December 12, 1940, Serial No. 369,720

8 Claims.

This invention relates to pressure regulating devices and more particularly to governors of the type for controlling the admission of steam to the fluid compressor of a fluid pressure system.

The above mentioned type of governor is used quite extensively in fluid pressure brake systems for railway vehicles and usually comprises a steam valve body, a cylinder section and a cap section. Mounted in the valve body is a steam valve which is operative to control the flow of steam to the steam driven compressor. This valve is controlled by a piston which is mounted in the cylinder of the cylinder portion and which is controlled by the pressure of fluid supplied irom a reservoir charged with fluid delivered by the compressor, the admission of fluid to the piston chamber being under the control of the usual regulating valve mechanism mounted in the cap section.

While this type of governor does function to control the action of the compressor in the manner intended, it has, in some cases and under some conditions, the objectionable characteristic of permitting the steam valve to unintentionally pulsate or vibrate in a vertical direction relative to the valve body. These pulsations areusually at a very high frequency, thereby producing a very objectionable noise and vibration and causing excessive wear of the valve controlling piston, piston bushing, valve stem and valve stem bearing. In some instances the valve may strike the valve seat formed on the body and when this occurs damage or excessive wear of the valve and valve seat results.

It was discovered that this pulsating action occurred when the steam valve was cracking open or closing, and then only when the governor was subjected to unavoidable shocks such as are commonly encountered in railway train operation.

In practice, when the pressure of fluid acting on the piston to maintain the steam valve closed reduces at a slow rate, the steam pressure acting on the under side of the valve will move the valve slowly from its seat. At the moment that the valve begins to leave its seat, steam flows from the under side to the upper side of the valve and consequently to the compressor. This flow around the valve will be at an extremely rapid rate, and as a result of this will effect a sudden momentary reduction in the steam pressure on the under side of the valve and at the same time effect .an increase in the pressure of steam on the upper side of the valve. This increased pressure nullifies, to a certain extent, the upward force of the valve, so that the pressure of fluid acting on the valve controlling piston causes the piston to operate to move the steam valve toward its seat. As soon as the valve moves in this direction the higher steam pressure on the under side of the valve again forces the valve upwardly. The downward movement 10 of the valve will again follow, and this alternate raising and lowering of the valve will continue until the pressure of fluid acting on the valve actuating piston has been reduced sufficiently to permit substantial equalization of the steam pressures on both sides of the valve. It

has been ascertained that once this objectionable pulsation of the valve commences it may continue for varying periods of time ranging from a few seconds to several minutes depending upon the rate of reduction in the pressure of fluid acting on the valve actuating piston.

The steam valve, as it nears thevalve seat on the body in its closing movement, restricts the flow of steam to the compressor. This causesa reduction in the pressure of steam acting on the upper side of the valve and also a v build-up'or increase in the steam pressure act- ,ing on the under side of the valve. Since the upper side of the valve is now partially unloaded the steam pressure acting on the under side of the valve will cause the valve to move upwardly. Upon such upward movement the rate of flow of steam to compressor and consequently to the upper side or" the valve will be increased thus increasing the load on the upper side of the valve, which loading and the resulting slight decrease of pressure acting on the under side of the valve will permit the valve controlling piston to act to again move the valve toward'its 40 seat. This pulsating or vibrating of the valve relative to its seat will continue at a very rapid rate until such time as the pressure of fluid acting on the valve controlling piston is sufiicientto maintain the valve seated against'the opposing steam pressure. j i The principal object of my invention is to provide a steam compressor governor of the above mentioned type with means for eliminating the unwanted and objectionable vibration of' the steam valve relative to itsseat. c

Other objects and advantages willappear in the following-1 more detailed description of the invention.v T g In the accompanying drawing Fig. 1 is a combined side elevational and sectional view of a steam compressor governor embodying the invention, the steam valve and associated moving parts being shown in valve open position; and

Fig. 2 is a fragmentary sectional view showing the steam valve in its seated position and the associated parts in their corresponding position.

It will here be understood that, whilst the steam compressor governor shown in the drawing is of the so-called single top type, the invention may be embodied in a steam compressor governor of the double top type.

The details and operation of the steam compressor governor shown in the drawing, with the exception of the improved construction whereby divides the interior of the body into a steam inlet chamber 5 and a steam outlet chamber 6, the inlet chamber being in communication with a pipe 1 leading from the steam supply, such for instance as a steam boiler (not shown) of a locomotive, and the outlet chamber being in communication with a pipe 8 leading to the usual steam driven fluid compressor (not shown).

This wall 4 is provided with a vertically extending steam passage 9, which passage, at its upper end, is surrounded by an annular valve 5 seat l0 provided in the wall. Directly above this passage and axially arranged in relation thereto, is an opening I l which is provided in the outer wall of the valve body. This opening ll communicates at its outer end with a circular recess formed on the exterior of the outer wall of the valve body.

Contained in the outlet chamber 6 is a steam valve I2 which is movable vertically into or out of seating engagement with the valve seat H) for controlling the flow of steam from the steam inlet chamber to the steam outlet chamber- This valve is provided with an upwardly extending stem I3 which is slidably guided in the central bore of a vertically disposed guide bushing I4. 5

The bushing is provided with an annular flange I5 which snugly fits in the exterior recess of the valve body l and rests on an annular gasket I6 carried by the outer wall of the body.

The lower end of the cylinder section 2 is provided with an annular boss H which rests on the flange l5 of the bushing and snugly fits in the exterior recess of the valve body. The section 2, and thereby the flange l5 are clamped to the valve body section by means of bolts [8 (two of which are shown), the gasket it making a steam tight seal between the steam outlet chamber 6 and the periphery of the flange l2.

Below the flange l5 the lower end portion of the bushing extends through the opening ll into the steam outlet chamber 6. The portion of the bushing which projects into the steam outlet chamber is provided with a downwardly depending wall 20 to provide a recess for the reception of the steam valve, the periphery of the valve having a sliding fit with the circular wall of the recess.

The steam valve is provided with an always open port 2| which extends vertically through the valve and which is for the purpose of permitting steam pressure to always equalize on opposite sides of the valve. The valve is also provided with a short vertically extending restricted steam supply port 22 which, at its lower end, is open to the under side of the valve and at its upper end is open to a laterally extending passage or port 23 leading to the periphery of the valve. When the valve is in its closed position on the seat ID as shown in Fig. 2 passage 23 is in communication with the steam outlet chamber 6 and when the valve is in itsopen position as shown in Fig 1, the passage is closed by the wall 23 of the recess.

The upper end portion of the cylinder section is hollow and mounted in this hollow portion is a vertically extending annular bushing 24 which is clamped in place when the head 3 is secured to section 2 by means of usual bolts not shown.

Interposed between the bushing 24 and an an- 0 nular ledge 25 of section 2 is a barrier member 26 which is preferably cup-shaped and which at its upper end is provided with an outwardly extending horizontally disposed annular flange 21 having portions 28 which rest on the annular ledge.

At spaced intervals the flange 2? is slit to provide relatively narrow sections which are bent upwardly from the main portion of the flange to form resilient lugs 29. These lugs are engaged by the lower endof the bushing 24 when the bushing is clamped in place, and through the medium of the lugs, the bushing acts to firmly clamp the flange 21 to the ledge 28. Below the flange 27 the barrier member is provided with an exhaust passage 3| which is always open to the atmosphere.

For controlling the operation of the steam valve there is operatively mounted in the bushing 24 a piston 32 having a stem 33 which loosely fits within a central longitudinal bore in the upper end portion of the stem of steam valve. At one side of the piston there is a chamber 34 and at the other side a chamber 35 which is always open to the atmosphere by way of the passage 3| in the barrier member. The chamber 34 is also constantly connected to the atmosphere by way of a choke plug 36, a chamber 38 which is formed by spacing the bushing 24, for a portion of its length, away from the casing of the section 2, the spaces between the lower end of the bushing 24 and the flat portions of the flange 21, and atmospheric chamber 34. This atmospheric communication is identical with the corresponding communication fully shown and described in the aforementioned Clyde 0. Farmer patent.

According to one feature of the invention the bushing 24 is provided with a vertically extending exhaust groove 39 through which the piston chamber 34 communicates with the atmospheric chamber 35 when the piston is in any position in which the steam valve is unseated, the piston in its valve seating position closing said communication, as will hereinafter more fully appear.

The governor top is mounted in the cylinder head 3 and may be identical with the top shown in the aforementioned Clyde C. Farmer patent, and briefly described may comprise a valve 40 that is operative at one time to supply fluid under pressure from a chamber 4!, which is in open communication with the usual main reservoir by way of a pipe 42, to the piston chamber 34, and at another time is operative to cut off such supply. This valve is controlled by means of a flexible diaphragm 43 which is subject on one side to pressure of a regulating spring and on 'stantially equal to each other and to the pres the otherside to the pressure of fluid in chamber M and the pressure of a light spring 45 Operation Assuming the main reservoir pressure to be low, the valve 49 will be maintained closed by the action of the regulating spring 44 of the governor top and the piston chamber 34 will be at atmospheric pressure, so that the pressure of steam acting on the under side of the steam valve [2 will maintain the steam valve open and thereby the piston in its upper position, all as shown in Fig. 1. With the steam valve open, steam flows from the steam inlet chamber 5 through passage 9 to the steam outlet chamber 6 and steam compressor causing the compressor to operate to supply fluid under pressure to the main reservoir.

It will here be noted that with the steam valve in itswide open position as shown, an enlarged portion 5d of the valve stem engages with the guide bushing, and by reason of such engagement the upper side of the valve will be maintained spaced away from the end wall of the recess provided in the bushing, so as to form a I chamber 5!, which chamber is open through the Now when the main reservoir pressure in the chamber 4| below the diaphragm 43, plus the pressure of the light spring 45, becomes slightly greater than the opposing pressure of the regulating spring M, the diaphragm is flexed upwardly permitting the light spring to unseat the valve 49 and thereby permit main reservoir pressure to flow from the chamber 4! to the piston chamber 35. chamber 34 causes the piston 32 to move downwardly and thereby seat the steam valve It so as to cut oii the steam supply to the compressor except for a slight amount which passes through the connected ports 22 and 23 in the steam valve Which port 23 is opened to the steam outlet chamber 6 just prior to theseating of the valve. This restricted supply of steam is just sufficient to keep the compressor operating slowly so as to keep the compressor warm and thereby avoid trouble from excessive steam condensation.

Fluid under pressur supplied to the piston chamber 3 3 will of course flow to the atmosphere by way of both the choke plug 36 and exhaust groove 3b in the piston bushing, but the supply of fluid to the chamber will be at a much faster rate than it is permitted to escape to the atmosphere, so that the rate of increase in the pressure of fluid in chamber 34 will not be materially retarded and the piston will promptly move toward its valve seating position.

As the steam valve l2 nears its seat, the flow of steam to the steam outlet chamber 6 is restricted by the valve, resulting in a reduction in the steam pressure in this chamber. Since the valve 12 is now in flow restricting position, a corresponding reduction in steam pressure will not be effected in the flow area or space between the valve and its seat It! and the pressure of steam acting on both sides of the valve ,willbesub- Fluid under pressure thus admitted tosure of steam in the inlet chamber.

It will here be understood that since th pressure of steam acting on the upper side of the valve I2 is not reduced when the reduction in the outlet chamber pressure occurs, the valve and controlling piston has no tendency to pulsate vertically and the piston continues to operate to steadily move the valve toward its seat. Just before the valve contacts with the valve seat ID the piston 32 cuts ofi the flow of fluid from the piston chamber 3 2 to chamber 35 by way of the exhaust groove 39 in the bushing, and as a consequence permits a more rapid increase in the pressure of fluid in the piston chamber 34. This results in the more rapid operation of the piston to finally seat the steam valve l2, in other words, the valv may close with a snap like action.

When the main reservoir pressure present in the chamber 34, together with the light spring 45 are no longer great enough to overcome the opposing pressure of the regulating'spring 44 the diaphragm 43 will be flexed downwardly, seating the valve 18, thereby cutting ofi the flow of fluid from the chamber ii to the piston chamber 34.

Fluid under pressure flowing from the piston chamber 3a to the atmosphere by way of the choke plug 36 now efiects a reduction in the pressure of fluid in the chamber and the steam pressure in the steam inlet chamber 5 and acting on the under side of the steam valve causes the steam valve and piston 32 to move upwardly. When the steam valve is moveda slight distance away from its seat, the piston 32 will have. been moved sufiiciently to uncover the exhaust groove 39 in the piston bushing to the atmospheric chamber 35, so that the fluid under pressure in the piston chamber 341, is quickly vented through the groove to the atmosphere. This permits the steam pressure acting on the under side of the steam valve to quickly move the valve to its full open position as shown in Fig. 1.

It will here be noted that when the steam valve i2 is cracked open, the resulting reduction in the pressure of steam in the steam inlet chamher 5 and the increase of steam in the steam outlet chamber 6 will have no effect upon the operation of the steam valve since the pressures on opposite sides of the valve are maintained substantially equal through the medium of the port 2| through the valve, and since no varying fluid differential can be created across the valve there will be no tendency for the valve to pulsate or vibrate vertically.

While one illustrative embodiment of the invention has been described in detail, it is not my intention to limit its scope to that embodiment or otherwise than by the pended claims. I

Having now described my invention, what I claim as new and desire to secure by Letters Patent is: g

1. A flow controlling valve device comprising an inlet chamber and an outlet chamber, a passage connecting said chambers, a recess in' said outlet chamber, a valve contained in said recess and movable vertically therein to open and close said passage; a communication extending through said valve for at all times ensuring the equalization of the pressures acting on opposite sides of the valve, and a restricted communication extending from the under side of said valve to the periphery thereof to provide for a flow of fluid from the inlet chamber to the outlet chamberwhen the valve is'in its passage closing poterms of the apsition, the last mentioned communication being closed at the periphery of the valve by a wall of the recess when the valve is in its passage opening position.

2. A flow controlling valve device comprising an inlet chamber and an outlet chamber, a passage connecting said chambers, a recess in said outlet chamber, a valve slidably fitting in said recess and movable vertically therein to open and close said passage, a communication extending through said valve for at all times ensuring the equalization of pressures acting on opposite sides of the valve, a piston responsive to the pressure of fiuid for actuating said'valve to close said passage, means operative to supply fluid under pressure for actuating said piston, and a I communication through which fluid acting on the piston may flow to the atmosphere, said piston, in its traverse to close said valve, cutting oil the flow of fluid through the last mentioned communication to accelerate the increase in the pressure of fluid acting on the piston at sub,- stantially the time the valve is about to close the communication for accelerating the final closing movement of said valve. 7

3. A flow controlling valve device comprising an inlet chamber and an outlet chamber, a passage connecting said chambers, a recess in said outlet chamber, a valve slidably fitting in said recess and movable vertically therein to open and close said passage, a communication extending through said valve for, at all times, ensuring the equalization of pressures acting on opposite sides of the valve, a piston responsive to the pressure of fluid for actuating said valve to close said passage, means operative to supply fluid under pressure for actuating said' piston, a communication through which fluid acting on the piston may flow to the atmosphere, said piston, in its traverse to close said valve, cutting off the flow of fluid through the last mentioned communication at substantially the time the valve is about to close the communication to accelerate the rate of increase in the pressure of fluid acting on the piston for thereby accelerating the final closing movement of said valve, said valve, upon a reduction in the pressure of fluid acting on said piston, being responsive to the pressure of fluid acting on the under side of the valve for opening said passage and for moving said piston, means for releasing the pressure of fluid acting on said piston, said piston upon an initial slight movement by said valve establishing the last mentioned communication to additionally vent the piston actuating fluid for thereby accelerating the movement of the piston and valve to their passage open position.

4. A fluid flow controlling valve device comprising a casing having an inlet chamber and an outlet chamber provided therein, a piston, a valve contained in said outlet chamber and operative at one time by the "pressure of fluid in said inlet chamber to admit fluid from the inlet chamber to the outlet chamber and operative. at another time by said piston under the influence of fluid pressure acting in opposition to the pressure of fluid in the inlet chamber to cut oil the major portion of the flow of fluid from the inlet cham ber to the outlet chamber, a stem for said valve,

2. guide bushing for said stem carried by said casing and having an end portion located within said outlet chamber, a recess provided in said end portion of the guide bushing for the reception of said valve and in which the valve has a the valve'and to at the same time isolate the upper side of the valve from said outlet chamber, and a passage extending through the valve to provide for the flow of fluid from one side of the'valve to the other.

5. A fluid flow controlling valve device comprising a ca ing having an inlet chamber and an outletchamber provided therein, a piston, a Valve contained in said outlet chamber and operative atone time by the pressure of fluid in said inlet chamber to admit fluid from the inlet chamber to the outlet chamber and operative at another time by said piston under the influence of a pressure acting in opposition to the pressure of fluid in the inlet chamber to cut off the major portion of the flow of fluid to the-outlet chamber, a recess for the reception of said valve, said recess having a circular wall with which said valve has a sliding fit so as to provide for the free movement of the valve and to, at the same time, isolate the upper side of the Valve from said outlet chamber, and a communication leading from one side of the valve to the other through which the pressure of fluid may, at all times, equalize on both sides of the valve.

6. In a steam compressor governor of the type comprising a steam valve body having a steam inlet chamber and a steam outlet chamber, a passage connecting said chambers, a steam valve mounted in said body and operative to one position to close said passage and operative to another position to open said passage, and a cylinder section, in combination, a piston mounted in said section for controlling th operation of said valve, a pressure chamber to which the face of the piston is exposed, a stem operatively connecting the piston and valve, an exhaust communication for said chamber arranged to be connected to the pressure chamber by said piston upon a short movement of the piston toward its valve open position and to be disconnected from the pressure chamber by the piston as the piston reaches a position in which said valve is closer to its passage closed position than to its passage full open position, and an annular wall located in the outlet chamber of said steam valve body, said steam valve having a sliding lit with the inner surface of said wall so as to permit the free movement of the valve and for, at the same time, isolating the upper side of the valve from said outlet chamber, and a communication extending from one side of the valve to the other to, at all times, insure the obtaining of an equalized steam pressure on both sides of the valve.

7. In a steam compressor governor of the type comprising steam valve body having a steam 111- let chamber and a steam outlet chamber, a passage connecting said chambers, a steam valve mounted in said body and operative to one position to close said passage and operative in another position to open said passage, and a cylinder section, in combination, a piston mounted in said section for controlling the operation of said valve, a pressure chamber to which the face of the piston is exposed, a stem operatively connecting the piston and valve, an exhaust communication from said chamber arranged to be connected to the pressure chamber by said piston upon a short movement of the piston toward its valve open position and be disconnected from the valve chamber by the piston as the piston reaches a position in which said valve is closer to its passage closedposition than to its passage full open position, an annular wall located within the out let chamber of said steam valve body, said steam valve having a sliding fit with the inner surface of said wall, a chamber defined by said valve and wall and isolated from the outlet chamber, and a communication extending from one side of the valve to the other to, at all times, ensure an equalized steam pressure in the last mentioned chamber and on the other side of the valve.

8. In a steam compressor governor of the type comprising a, steam valve body having a steam inlet chamber and a steam outlet chamber, a passage connecting said chambers, a steam valve mounted in said outlet chamber and operative to one position to close said passage and operative to another position to open said passage, and a cylinder section, in combination, a piston mounted in said section for controlling the operation of said valve, a pressure chamber to which the face of the piston is exposed, a stem operatively connecting the piston and valve, an exhaust communication in said chamber arranged to be connected to the chamber by said piston upon a short movement of the piston toward its valve open position and to be disconnected from the chamber by the piston as the piston reaches a position in which said valve is closer to its passage closed position than to its passage full open position, a pressure chamber at the upper side of the valve and isolated from said steam outlet chamber, and a communication providing for the free equalization of steam pressures in said pressure chamber and on the under side of said valve.

WILLIAM DUCKWORTH. 

